Photoelectric conversion device

ABSTRACT

A photoelectric conversion device taking the form of a thin film and having a substrate exhibiting poor thermal resistance. The device prevents thermal deformation which would normally be caused by local application of excessive heat to the substrate. The device has output terminals permitting the output from the device to be taken out. The output terminals are formed on the surface of the substrate opposite to the photoelectric conversion device. The device further includes electrical connector portions for electrically connecting the electrodes of the device with the output terminals. The present invention also provides a method of treating a substrate having poor thermal resistance with a plasma with a high throughput. The substrate is continuously supplied into a reaction chamber and treated with a plasma. This supply operation is carried out in such a way that the total length of the substrate existing in a plasma processing region formed by electrodes is longer than the length of the electrodes.

This is a divisional of application Ser. No. 09/149,289 filed on Sep. 9,1998, now U.S. Pat. No. 6,720,576, which is a divisional of applicationSer. No. 08/554,241 filed on Nov. 8, 1995, now U.S. Pat. No. 5,821,597,which is a divisional of application Ser. No. 08/118,672 filed on Sep.9, 1993, now abandoned.

FIELD OF THE INVENTION

The present invention relates to a photoelectric conversion devicehaving a novel structure and, more particularly, to a photoelectricconversion device employing a flexible substrate having poor thermalresistance. Also, the invention relates to processing of this flexiblesubstrate such as formation of a coating on the substrate and, moreparticularly, to a method of treating the flexible substrate with aplasma when a solar cell or the like is fabricated by the use of aflexible organic film instead of a solid substrate.

BACKGROUND OF THE INVENTION

The market has required smaller, thinner, and even lighter electronicand electric parts. Various materials have begun to be used to fabricatethese parts.

Photoelectric conversion devices such as solar cells also show such atendency, and devices of various specifications have been proposed.Among others, thin and light devices using a substrate made of aflexible organic or metal film have attracted attention because of thepossibility of application to other electrical appliances and industrialmachines.

Of photoelectric conversion devices using these flexible substrates,photoelectric conversion devices employing substrates made of organicmaterials have attracted attention because of their cost,characteristics, and workability. Photoelectric conversion devices ofthis type have begun to become the mainstream of photoelectricconversion devices having flexible substrates. Flexible substrates madeof organic materials have numerous advantages of having high workabilityand being light in weight over substrates made of thin metal materials.

The structure of a photoelectric conversion device using a flexiblesubstrate made of such an organic material is diagrammatically shown inFIG. 7, where three photoelectric elements are connected in series on aflexible substrate 1 to form an integrated photoelectric conversiondevice. Each of the photoelectric elements comprises a first electrode71, a semiconductor layer 72 consisting of a non-single crystal, andsecond electrodes 73, 74. In this example, light impinges on the secondelectrodes. Therefore, one second electrode 73 is made of an ITO that isa transparent electrode material. The other second electrodes 74 aregrid-like auxiliary electrodes. The second electrodes 74 are connectedwith the first electrodes 71 of adjacent photoelectric conversionelements. The elements are connected in series. The output from thisphotoelectric conversion device is developed between copper leads 75which are soldered to the second electrodes.

Substrates having poor thermal resistance such as the aforementionedflexible substrates made of organic materials are not sufficientlyresistant to heat compared with substrates made of other materials.Polyimide film which is said to be resistant to heat can withstand hightemperatures of about 300 to 350° C. at best. For this reason, whenphotoelectric conversion devices are manufactured, application of heatis avoided as fully as possible. This method has been put into practicaluse.

However, after a photoelectric conversion device is fabricated, outputleads must be provided to permit the use of the device. The output leadsare connected with the second electrodes normally by soldering. To fusethe solder, it is necessary to apply heat locally.

Consequently, excessive heat is applied to only a part of the organicmaterial of the flexible substrate. As a result, only this part deformsthermally. If the leads are bonded to the electrodes of thephotoelectric conversion device at a temperature at which no thermaldeformation takes place, then a sufficient bonding strength cannot beobtained. Under this condition, the electrical conduction deteriorates,or the bonded portions peel off, thus impairing the reliability. Hence,it is desired to improve these output leads.

Where a photoelectric conversion device is fabricated from such aflexible material by the prior art techniques, handling of the substratehas posed problems. Especially, where a semiconductor coating or thelike is formed by chemical vapor deposition or other similar method, theflexibility of the substrate presents problems. Therefore, when such asubstrate is used, the production facility has been required to have aspecial means for holding the substrate, unlike the case in which othersolid substrates are employed.

A so-called roll-to-roll method has been generally accepted as a methodof holding the substrate. This method begins with pulling out a flexiblesubstrate from a roll. The substrate is fed into a plasma processingapparatus or plasma processing chamber, where the substrate isprocessed. Then, the substrate is rewound into a roll.

In the case of a plasma processing machine making use of theconventional roll-to-roll method, a substrate is placed substantiallyparallel to electric discharge electrodes located in a region whereplasma processing is performed. The substrate is slowly and continuouslysupplied from the roll and passed through the processing region to treatthe substrate with a plasma.

One example of this machine is disclosed in Japanese Patent Laid-OpenNo. 34668/1984. This disclosed machine is designed to form a film. Thereaction chamber of this machine and its vicinities are schematicallyshown in FIG. 9, where a flexible substrate 201 is wound into a roll220. The substrate is continuously fed into the reaction chamber, 221,from the roll 220. A pair of parallel-plate electrodes 222, 223, areactive gas supply system 225, and an exhaust system 226 are mountedinside the reaction chamber 221. The continuous flexible substrate 201passes over or by the cathode of the parallel-plate electrodessubstantially parallel to them. In this structure, a film is formed onthe substrate. The substrate may also be positioned on the side of theanode and processed. The substrate 201 supplied in this way is treatedwith a plasma while passing through the processing region close to theelectrodes. That is, the substrate is treated with a plasma or a film isformed while the substrate stays in the processing region.

In the known plasma processing machine described above, a set ofdischarge electrodes can treat only one roll of substrate. Hence, thethroughput of the plasma processing is low. In the case of silicon of anon-single crystal used for photoelectric conversion device, a film isgrown at a rate within a range from 0.1 to 10 Å/sec to secure therequired semiconductor characteristics, i.e., to prevent the filmquality from deteriorating. It is usually necessary that a semiconductorfilm of a photoelectric conversion device have a thickness of about 0.3to 2 μm. Therefore, the substrate must stay in the processing region fora long time. In consequence, the plasma processing region, or theelectrodes, must be made long, or the substrate must be passed throughthe region at a quite low speed.

Where the electrodes are made long, the dimensions of the reactionchamber are increased. That is, the plasma processing machine occupies alarge area. This is a heavy burden on mass production. If the substrateconveyance speed is decreased, the throughput of the plasma processingdrops, thus hindering mass production. More specifically, in the case ofthe above-described semiconductor consisting of a non-single crystal, ifa film 1 μm thick should be formed within a reaction chamber about 1 mlong at a deposition rate of 1 Å/sec, then the substrate is transportedat 0.1 mm/sec. If a roll having a length of 100 m is treated, as long asabout 278 hours are required.

Consequently, there is a demand for a machine which relies on theroll-to-roll method and treats substrates at a higher speed or improvesthe throughput of the machine. Whether electronic devices using flexiblesubstrates can be mass-produced or not depends heavily on this point.

SUMMARY OF THE INVENTION

The present invention resides in a photoelectric conversion device whichtakes the form of a thin film and is formed on a substrate having poorthermal resistance e.g. an organic resin substrate. The device hasoutput terminals to permit the output from the device to be taken out.The output terminals are mounted on an opposite surface of saidsubstrate to the surface of the substrate on which the device is formed.The photoelectric conversion device further includes electricalconnector portions (conductors) for electrically connecting the outputterminals with the electrodes of the device.

In one feature of the invention, the substrate of the photoelectricconversion device described just above is flexible, and the electricalconnector portions are located in holes (openings) formed in theflexible substrate.

In another feature of the invention, the substrate of the photoelectricconversion device described just above is flexible, and the electricalconnector portions are located at end surfaces of the flexiblesubstrate, that is, the electrical connector portions are provided onsides of the flexible substrate.

Also, the present invention resides in a photoelectric conversion devicewhich takes the form of a thin film, is formed on a substrate havingpoor thermal resistance, and has output terminals and electricalconnector portions. The output terminals permit the output from thedevice to be taken out, and are mounted on a surface opposite to thesurface of the substrate on which the device is formed. The electricalconnector portions electrically connect the electrodes of the devicewith the output terminals, and are made of the same material as portionsof the electrodes of the device.

In any of the novel photoelectric conversion devices described above,output leads are provided to permit the output from the photoelectricconversion device to be taken out. When the device is provided with theoutput leads, the leads are bonded to the device independent ofelectrical connection of the leads with the electrodes of the device.Thus, a sufficient bonding strength is accomplished without applyinghigh temperature locally. Therefore, the output terminals are mounted onthe surface of the substrate opposite to the photoelectric conversiondevice. The output terminals are bonded to the substrate. The bondedoutput terminals are electrically connected with the electrodes of thedevice by an electrically conductive material. In this way, the outputterminals having sufficient bonding strength can be mounted withoutapplying excessive heat to the substrate which has poor heat resistance.

The present invention is also intended to solve the aforementionedproblems. It is an object of the invention to provide a method oftreating flexible substrates with a plasma with a high productivity. Inorder to treat the flexible substrate with a plasma, the substrate iscontinuously supplied into a reaction chamber in such a way that thetotal length of the substrate existing in a plasma processing regionformed by electrodes is longer than the length of these electrodes.

A plasma processing method in accordance with the present inventioncomprises the steps of:

-   -   exposing a substrate to a plasma generated adjacent to an        electrode provided in a chamber (or a plasma generated adjacent        to an electrode and enclosed within a frame structure provided        in a chamber) in order to perform a plasma processing on said        substrate; and    -   conveying said substrate during said plasma processing,    -   wherein length of said substrate in said plasma is longer than        that of said electrode. Said substrate can be moved from a roll        to another roll.

One example of method of supplying the flexible substrate in such a waythat the total length of the substrate existing in a plasma processingregion formed by electrodes is longer than the length of theseelectrodes is illustrated in FIG. 8, where the flexible substrate, 201,is made to take a zigzag course within the plasma processing region,204, between a pair of electrodes 202 and 203 by rollers such as 205. Inthis case, the total length of the flexible substrate 201 existinginside the plasma processing region is increased as the number of turnsis increased.

The conventional method utilizing the prior art roll-to-roll scheme astypically shown in FIG. 9 makes use of the dark portion close to thecathode or anode for plasma processing. On the other hand, the presentinvention makes positive use of a positive column produced by a plasmadischarge, thus improving the productivity of the plasma processing. InFIG. 8, the flexible substrate is supplied substantially perpendicularto the surfaces of the discharge electrodes 202 and 203. The directionof supply is not limited to this direction. Similar advantages can beobtained by supplying the substrate parallel or at an angle to thesurfaces of the electrodes as long as the total length of the substratestaying in the plasma processing region is longer.

Where a coating is formed by plasma processing, the surface of thesubstrate is preferably parallel to the direction of gravity. Inparticular, when a coating is formed, dust and flakes are produced.Therefore, if the surface of the substrate is parallel to the directionof gravity, then the dust and flakes are prevented from depositing ontothe substrate. Hence, the surface of the substrate can be made clean.Also in this case, the angular relation between the substrate surfaceand the electrode surface can be set at will.

The novel method of treating a flexible substrate with a plasma makesuse of a positive column more positively in the manner described now. Aplasma discharge region is established which has such a frame structureas to confine a plasma discharge within a reaction chamber where plasmaprocessing is performed. The substrate is continuously supplied into theframe structure so that the substrate takes a zigzag course. Inconsequence, a high productivity can be achieved. Especially, thisstructure can make the plasma discharge region uniform and hence canrealize homogeneous plasma processing.

Since the novel method makes positive use of an electric discharge in apositive column, two rolls of substrate can be supplied in aback-to-back relation into the plasma processing region. In this case,the throughput can be doubled exactly. However, it is necessary to holdthe surfaces of the substrates by rollers or the like in order that eachsubstrate take a zigzag route. For this purpose, the surface of eachsubstrate is not totally held but rather partially supported.

The total length of plural substrates existing in the plasma processingregion can be made longer than the electrodes by supplying thesubstrates parallel to the electrodes without taking a zigzag course. Inthis case, numerous facilities for supplying the substrates arenecessary but this method has the advantage that the rolls do notdirectly touch the substrate surfaces.

Other objects and features of the invention will appear in the course ofthe description thereof, which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A)–1(C) are schematic cross sections of a photoelectricconversion device according to the invention;

FIGS. 2–6 are cross sections of a photoelectric conversion deviceaccording to the invention, illustrating successive steps performed tofabricate the device;

FIG. 7 is a schematic cross section of a known photoelectric conversiondevice;

FIG. 8 illustrates a plasma processing method according to theinvention;

FIG. 9 illustrates a known plasma processing method;

FIG. 10 illustrates another plasma processing method according to theinvention;

FIG. 11 illustrates a further plasma processing method according to theinvention; and

FIG. 12 illustrates a yet other plasma processing method according tothe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF INVENTION EXAMPLE 1

FIG. 1(A) shows an integrated photoelectric conversion device accordingto the invention. This photoelectric conversion device is composed of aflexible substrate 1 made of plastic film, a first electrode 2, aPIN-type photoelectric conversion layer 3, second electrodes 6, 7, andinsulators 4, 5. The insulators 4 and 5 consist of epoxy resin.

The photoelectric conversion device has photoelectric elements 101, 102,and 103. The second electrode 7 of the photoelectric element 101 iselectrically connected with the first electrode 2 of the photoelectricelement 102 by a connector portion 9. The device is provided with afirst groove 8 to isolate the first electrode of the first photoelectricelement from the photoelectric conversion layer of the secondphotoelectric element 102. The second electrodes 6 of these elements 101and 102 are insulated from each other by a groove 10 formed by a laserscriber.

Simultaneously with formation of the second electrode 7 for obtaining anintegrated structure, the output of the photoelectric element 101 on theside of the substrate is brought out onto the photoelectric conversionlayer and connected with an outgoing electrode 15. The output of thesecond electrode of the photoelectric element 103 is connected with anoutgoing electrode 14 extending from the second electrode 7.

In the present example of photoelectric conversion device, a connectorhole (opening) 11 has a connector portion 12 and extends through bothphotoelectric conversion layer and substrate which underlie the outgoingelectrodes 14 and 15. These outgoing electrodes 14 and 15 are connectedwith output terminals 13 formed on the back surface of the device viathe connector portion 12. This connector portion 12 is made of the samematerial as the second electrode 7. Thus, the output from the presentphotoelectric conversion device can be taken out from the outputterminals 13 formed on the opposite surface of the substrate 1 to asurface on which the photoelectric elements are provided.

A method of fabricating the present example of photoelectric conversiondevice is described below by referring to FIG. 2 and ensuing figures.First, chromium was sputtered on the flexible substrate 1 to form thefirst electrode 2 having a thickness of 2000 Å. The substrate 1 was madeof plastic film. In the present example, the plastic film consists ofpolyethylene terephthalate.

To form the chromium film, a DC magnetron sputtering machine wasemployed under the following conditions:

Partial pressure of argon: 6×10⁻³ torr

DC current: 1 A

Substrate temperature: The substrate was not heated.

Then, the photoelectric conversion layer 3 was fabricated from siliconconsisting of a non-single crystal. No restrictions are imposed on thephotoelectric conversion layer. However, when the thermal resistance ofthe plastic film substrate is taken into account, it is desired to adopta method which permits the substrate temperature to be set below 100° C.

In the present example, silicon semiconductor layers of N-type, I-type,and P-type were deposited successively in this order from the side ofthe substrate to form a PIN-type photoelectric conversion layer having athickness of 4500 Å as the photoelectric conversion layer 3. None ofthese silicon semiconductor layers were made of a single crystal.Plasma-assisted CVD was used for this purpose and carried out under thefollowing conditions:

(1) The N-type Semiconductor Layer Having a Thickness of 400 Å wasFormed Under the Following Conditions:

Substrate temperature: 80° C.

RF power: 10 W (13.56 MHz)

Pressure during deposition process: 0.04 torr

Gas flow rates: SiH₄=15 sccm (containing 1% PH₃)

-   -   H₂=150 sccm        (2) The I-type Semiconductor Layer Having a Thickness of 4000 Å        was Formed Under the Following Conditions:

Substrate temperature: 80° C.

RF power: 10 W (13.56 MHz)

Pressure during deposition process: 0.04 torr

Gas flow rates: SiH₄=15 sccm

-   -   H₂=150 sccm        (3) The P-type Semiconductor Layer Having a Thickness of 100 Å        was Formed Under the Following Conditions:

Substrate temperature: 80° C.

RF power: 10 W (13.56 MHz)

Pressure during deposition process: 0.04 torr

Gas flow rates: SiH₄=16 sccm (containing 1% B₂H₆)

-   -   CH₄=18 sccm    -   H₂=145 sccm

After the condition illustrated in FIG. 2 was obtained, four firstgrooves 8 were formed by a laser scriber in a laminate consisting of thefirst electrode 2 and the photoelectric conversion layer 3. The scriberused a KrF excimer laser emitting a wavelength of 248 nm. To cut thefirst grooves, the laser emitted 7 shots of laser radiation, each havingan energy of 1.0 J/cm².

In the present example, the laser beam was transformed into a linearform by optics, and each one shot produced a linear groove.Alternatively, a laser beam spot may be swept along a straight line tocut each groove.

An ArF excimer laser, an XeF excimer laser, a YAG laser, or the like canbe used, depending on the application, for the laser scriber. Asmentioned previously, the wavelength of the laser is preferably shorterthan 600 nm. However, a YAG laser emitting a wavelength of 1.06 μm canalso be used.

Importantly, the laminate consisting of the first electrode 2 and thephotoelectric conversion layer 3 is scribed, unlike in the prior arttechniques. Therefore, during laser scribing of the first electrode,occurrence of peeling from the plastic film substrate, fine splits, andflakes can be suppressed greatly.

Then, as shown in FIG. 3, epoxy resin (an insulator) was printed to athickness of 2 to 20 μm at given locations 4 and 5 by screen printing.In this way, the first grooves 8 were filled with the epoxy resin 4 thatis an insulator. At the same time, the layer 5 of the insulator, orepoxy resin, was formed on the photoelectric conversion layer 3. The useof screen printing permits the insulator layers 4 and 5 to besimultaneously formed. This simplifies the patterning step which wouldnormally often cause defects. Furthermore, in the novel method, thepatterning step is done simply to process the insulator and so thesuppression of defects in the insulator in the patterning step usingscreen printing contributes greatly to an improvement in the productionyield.

In the present example, epoxy resin was used as an insulator because itcan be easily processed. As long as an insulator is used, norestrictions are imposed on the material. Examples include siliconoxide, organic resins such as polyimide and silicone rubber, urethane,and acrylic resin. Since the material is irradiated with laser radiationin the subsequent laser scribing step, the material has preferably suchthermal resistance that it neither burns out nor sublimes when exposedto weak laser radiation. Materials which totally transmit the laserradiation are not desirable.

In this manner, the condition illustrated in FIG. 4 was obtained. Theactual positions of the grooves 8 and the insulators 4 and 5 aredetermined by the accuracies of the patterning step (the screen printingin the present example) and of the laser scribing step. Obviously, thesepositions are not limited to the illustrated geometrical relation.

After deriving the condition shown in FIG. 4, the second electrodes 6were deposited as a 2000 Å-thick layer by vacuum evaporation. The secondelectrodes 6 were made of ITO. Any other material such as SnO₂ or ZnOcan be used as long as it transmits light. Also, various methods can beexploited to form the second electrodes. Where a plastic film substratehaving poor thermal resistance is used as in the present example, alow-temperature process which does not thermally affect the substrate ispreferably employed.

Grooves 10 were formed in the second electrodes 6 formed on theinsulator layer 5 by laser scribing to cut the second electrodes 6 asshown in FIG. 4. Importantly, the insulator layer 5 shields thephotoelectric conversion layer 3 against the laser radiation. In thepast, in a laser scribing step for cutting only this transparentconductive film, the underlying photoelectric conversion layer 3 and thefirst electrode 2 have been often machined simultaneously. In this case,these two layers together form an alloy, thus producing a short circuit.This has made it difficult to pack numerous elements into an integratedcircuit. On the other hand, in the present invention, the insulatorlayer 5 protects the underlying layer 3 against the laser radiation.Consequently, the insulator layer 5 prevents the laser beam fromscribing the photoelectric conversion layer 3. In addition, this assuresthat the rear electrode is cut. Hence, quite high reproducibility andimproved production yield can be obtained.

Thereafter, connector holes 11 were cut by a laser beam around thephotoelectric elements in such a way that the holes 11 extended throughthe second electrodes 6, the photoelectric conversion layer 3, the firstelectrode 2, and the substrate 1. Since the holes 11 extended throughthe substrate, it had to be left to such an extent that it can be held.In the present example, the connector holes were formed by the use of aYAG laser in such a manner that the total area of the connector holesaccounted for 30% of the area of the surrounding conducting region.

Copper sheets 13 were bonded with an epoxy resin to the surface of thesubstrate opposite to the surface having the connector holes. As aresult, the portions excluding the connector holes were firmly bonded.

A grid-like auxiliary electrode 7 was then formed on the secondelectrodes 6 such that the electrode 7 forms portions of the secondelectrodes 6. The auxiliary electrode 7 was shaped like a comb on thelight-receiving surface and shaped like rods substantially over onewhole surface at locations where adjacent elements are connectedtogether.

The pattern of the auxiliary electrode 7 was improved and formed up tothe vicinities of the connector holes 11 around the photoelectricelements to form outgoing electrodes 14 and 15. This auxiliary electrode7 was patterned with silver paste by screen printing. In this manner,connector portions 12 were formed. Thus, the state shown in FIG. 5 wasobtained.

This auxiliary electrode 7 was thermally treated at 100° C. for 50minutes and sintered to complete the auxiliary electrode 7 and to formthe connector portions 12. This permits the output from thephotoelectric conversion device from being taken out from the outputterminals 13 mounted at the rear surface of the substrate.

Then, the second electrodes 6 and 7 on which the auxiliary electrode 7was formed were connected with the first electrode of adjacentphotoelectric elements. For this purpose, a YAG laser beam wasilluminated from the side of the second electrodes 6 and 7 to melt anddiffuse the material of the second electrodes. The second electrodespassed through the semiconductor layer 3 and connected with the firstelectrodes. The wavelength of the YAG laser was 1.06 μm. The oscillationfrequency of the Q switch of the laser was 2 KHz. The energy was 0.2 W.The electrically connected portions were scanned at a speed of 10 mm/secto form junctions 9 at which the second electrodes 6 and 7 wereconnected with the first electrodes 2. In this way, the present exampleof photoelectric conversion device was completed by the steps describedthus far.

This structure permits the output terminals 13 of the photoelectricconversion device to be directly bonded to the substrate via a strongadhesive. Hence, a sufficient adhesive strength could be obtained.Furthermore, a sufficiently good connection with the electrodes could bemade by Ag paste. The output terminals of the photoelectric conversiondevice could be fabricated without heating the device locally. Since theoutput terminals were mounted on the rear surface of the substrate, theoutput was supplied to the outside within the area of the device. Thearea of the surrounding portions used for taking out the output could bereduced.

The photoelectric conversion layer 3 can also be formed by theroll-to-roll method. In particular, three plasma processing machinessimilar to the machine shown in FIG. 10 are used. These machines areconnected in turn to form a P-type semiconductor layer, an intrinsicsemiconductor layer, and an N-type semiconductor layer, respectively. Inthis way, the photoelectric conversion layer 3 is formed.

EXAMPLE 2

This example of photoelectric conversion device takes a form asillustrated in FIG. 1(B). In this structure, connector portions 12 usedto connect the second electrodes 7 with output terminals 13 located onthe rear surface of the substrate are formed at the end surfaces of thesubstrate. Other manufacturing steps are similar to the correspondingsteps of Example 1 but the laser illumination steps for piercing thesubstrate is dispensed with.

Since the end surfaces of the substrate are used as the connectorportions 12, the output terminals 13 are adhesively bonded to the rearsurface of the substrate so as to protrude from the substrate. Thisexample yields the same advantages as Example 1 but is able to reducethe number of manufacturing steps. Unlike Example 1, the connectorportions 12 do not have limited size. Therefore, the reliability ofconnection and the production yield can be improved further.

EXAMPLE 3

This example of photoelectric conversion device takes a form asillustrated in FIG. 1(C). In this structure, connector portions 12 usedto connect the second electrodes 7 with output terminals 13 located onthe rear surface of the substrate are formed on the end surfaces of thesubstrate. Unlike Example 2, the connector portions 12 are not made ofthe same material as the second electrodes 7. Rather, the connectorportions 12 are made of the same material as the output terminals 13formed on the rear surface of the substrate. These connector portions 12made of a metal are located on opposite sides of the substrate and clampit therebetween. Other manufacturing steps are similar to thecorresponding steps of Example 1 but the laser illumination step forpiercing the substrate is dispensed with.

Each metal clamp acting as one connector portion 12 and also as oneoutput terminal 13 takes a U-shaped form with respect to the crosssection of the photoelectric conversion device. Hence, the metal clampsare more firmly mounted to the substrate. Of course, an adhesive mayalso be used to bond the clamps with the substrate if necessary.

If the clamps simply clamp the substrate therebetween, then theelectrical connection with the second electrode 6 is not satisfactory.Therefore, the second electrodes 7, or auxiliary electrodes, are made toextend to the surfaces of the clamps so that the clamps are connectedwith the second electrodes 6 and 7. In this way, satisfactory connectioncan be made.

In the structure of this example, not only the rear surface of thesubstrate but also the end surfaces of the substrate are used to takeout the output. This facilitates mounting this photoelectric conversiondevice into a product with the device used as an auxiliary power supply.

In the three examples described thus far, photoelectric conversiondevices having a given integrated structure has been described. Theinvention is not limited to this integrated structure. Of course, theinvention can be applied to other structures.

EXAMPLE 4

FIG. 10 schematically shows the reaction chamber of a machine and itsvicinity, the machine embodying a method of processing a substrate inaccordance with the present invention. Two rolls of PET film having athickness of 200 μm and a width of 200 mm are used as flexiblesubstrates 201. These two rolls are continuously supplied into thereaction chamber, 230, while held in a back-to-back relation. Thesubstrates 201 taking the form of rolls 231 are positioned in aback-to-back relationship to each other. These rolls 231 are held byrollers and made to take a zigzag course such that each substrate passesa discharge region 235 between a pair of electrodes 233 and 234 fivetimes. In the present example, the electrodes and the substrates arearranged as shown in FIG. 8 and so the electrodes 233 and 234 areparallel to the plane of the drawing. Since these electrodes cannot beshown, their positions are schematically indicated by a broken line. Thetime for which one substrate stays within the plasma processing region235 can be increased fivefold compared with the prior art method. Inaddition, two substrates are supplied while held in a back-to-backrelation and, therefore, the throughput of the whole machine can beincreased by a factor of 10.

Where this machine is used to build a solar battery of a non-singlecrystal semiconductor on a flexible substrate, plural reaction chambersas shown in FIG. 10 are required to be connected together. Morespecifically, reaction chambers used to form a P-type semiconductor, anI-type semiconductor, and an N-type semiconductor, respectively, areconnected in turn. Semiconductor films are formed by continuouslysupplying a substrate into the spaces between the reaction chambers.

Each reaction chamber is equipped with a reactive gas supply system, agas discharge system, and a substrate-heating means. The P-type, I-type,and N-type semiconductors-differ in thickness. However, the speed atwhich the substrate is conveyed cannot be made different among thereaction chambers, because the substrate is supplied continuously.Therefore, the length of the substrate existing in each different plasmaprocessing region is made different so that the substrate may stay ineach different plasma processing region of the reaction chambers for adifferent time. In consequence, films having different thicknesses canbe realized at a constant conveyance speed without making the reactionchambers different in length.

EXAMPLE 5

FIG. 11 shows another machine which is similar to the machine alreadydescribed in connection with FIG. 10 with respect to the structure forsupplying substrates but differs in the following points. Rolls 249 forsupplying substrates are mounted adjacent to a reaction chamber andinside a substrate supply chamber 241 which is shielded from the outsideso as to have the same pressure or ambient as the inside of the reactionchamber. Similarly, rolls 249 for winding up the substrates are mountedadjacent to the reaction chamber and inside a substrate take-up chamber242 which is shielded from the outside so as to have the same pressureor ambient as the inside of the reaction chamber.

The substrates 201 make plural turns between electrodes 246 and 247 tocause the substrates to stay for a long time, in the same way as inExample 4. The discharge space in the plasma processing region where thesubstrates stay is confined by electrode hoods 243, 245 mounted at theback of the electrode pair and also by a frame 244 having slitspermitting passage of the substrates. A plasma is confined within thislimited space.

The ambient of the plasma can be made uniform by fabricating theelectrode hoods and the frame out of the same material or by puttingthem at the same potential. In consequence, a homogeneous plasmadischarge can be accomplished. As a result, substrates can be uniformlytreated with a plasma, or uniform films can be formed on the substrates.Also, even if the electrode spacing is increased, the ambient of theplasma can be made uniform. This enables a stable plasma discharge, thusincreasing the time for which the substrates stay.

In the examples described above, substrates are supplied from one sideand wound up on the other side to cause them to stay for a long time ina plasma processing region. The present invention is not limited to thisstructure. An alternative structure is shown in FIG. 12, wheresubstrates are supplied from one side, turned back inside the plasmaprocessing region, and wound up on the same side. Specifically, rolls251 for a zigzag movement and rolls 251 for turning back the substratestherearound are mounted in the plasma in a reaction chamber 250. Thesubstrates are conveyed in a back-to-back relation in alternatedirections.

As shown in FIGS. 10 and 11, a plasma processing method in accordancewith the present invention comprises the steps of:

-   -   generating a plasma in a reaction chamber;    -   extending a substrate across said chamber to expose a surface of        said substrate to said plasma; and    -   treating said substrate with said plasma,    -   wherein a passage of said substrate is bended at least one point        within said plasma in order that an effective area of said        substrate treated with said plasma is increased.

Said plasma can be formed between a pair of electrodes. Said substrateis continuously moved through said chamber during said treating.

In the structures shown in FIGS. 10 and 11, plural reactions can beeasily carried out successively by connecting together plural reactionchambers. In the structure shown in FIG. 12, each substrate alwayspasses through the same ambient twice and, therefore, even if thedistribution of plasma discharge is not uniform, the substrate undergoesuniform processing.

Any of these structures is a substrate supply system which improves thethroughput of plasma processing. These structures can be appropriatelyselected, depending on the form and nature of the required plasmaprocessing.

The present invention makes it possible to form output terminals on aflexible substrate having poor thermal resistance with good bondingstrength and sufficient electrical connectivity without soldering. Inthis way, a photoelectric conversion device comprising a substrate freeof distortion and warpage can be realized. Furthermore, the presentinvention enables plasma processing which utilizes a high-productivityroll-to-roll method without the need to increase the dimensions of themachine or to decrease the speed at which the substrate or substratesare conveyed.

1. A photoelectric conversion device comprising: an organic resinsubstrate having a front surface and a rear surface; a plurality ofseries connected photovoltaic elements formed over said organic resinsubstrate, each of said photovoltaic elements comprising: a firstelectrode formed over the front surface of said organic resin substrate;a photoelectric conversion semiconductor layer provided over said firstelectrode; and a second electrode formed over said photoelectricconversion semiconductor layer; an output terminal provided on the rearsurface of said organic resin substrate; and a conductor connecting saidoutput terminal with the second electrode of one of the photovoltaicelements, wherein said conductor extends on one side edge of the organicresin substrate.
 2. The photoelectric conversion device of claim 1wherein said substrate is flexible.
 3. The photoelectric conversiondevice of claim 1 wherein said photoelectric conversion semiconductorlayer has a PIN junction.
 4. A photoelectric conversion devicecomprising: an organic resin substrate having a front surface and a rearsurface; a first electrode formed over said front surface; aphotoelectric conversion semiconductor layer provided over said firstelectrode; a second electrode formed over said photoelectric conversionsemiconductor layer; an output terminal provided on the rear surface ofsaid substrate; and a conductive layer formed on said second electrodeand extending around a side surface of the substrate to contact saidoutput terminal, thereby, electrically connecting said output terminalwith said second electrode.
 5. The device of claim 4 wherein saidorganic resin substrate is flexible.
 6. The photoelectric conversiondevice of claim 4 wherein said photoelectric conversion semiconductorlayer has a PIN junction.
 7. A photoelectric conversion devicecomprising: an organic resin substrate having a front surface and a rearsurface; a first conductive film formed over the front surface of saidsubstrate; a photoelectric conversion layer formed over said firstconductive film; a first groove formed through said photoelectricconversion layer and said first conductive film in order to electricallydivide said conductive film and said photoelectric conversion layer; afirst insulating strip filling said first groove; an opening formedthrough said photoelectric conversion layer and reaching to said firstconductive film; a second conductive film formed on said photoelectricconversion layer and covering said first insulating strip; a conductivematerial filled in said opening to connect said first conductive filmand said second conductive film; a second groove formed through saidsecond conductive film in order to electrically divide said secondconductive film, said opening being located between said first grooveand said second groove; an output terminal provided on the rear surfaceof said substrate; and a conductor connecting said output terminal andsaid second conductive film, wherein said conductor is connected to saidoutput terminal around a side surface of the organic resin substrate. 8.A photoelectric conversion cell comprising: an organic resin substratehaving a front surface and a rear surface; a first conductive filmformed over the front surface of said substrate; a photoelectricconversion semiconductor layer formed on said first conductive film; asecond conductive film formed over said photoelectric conversionsemiconductor layer; first and second insulators formed through at leastsaid conversion layer with a photoelectric conversion element definedtherebetween; an output terminal formed on the rear surface of saidsubstrate; and a conductive layer formed on the second conductive filmand electrically connecting said second conductive film and said outputterminal, wherein said conductive layer extends on one side edge of theorganic resin substrate.
 9. A photoelectric conversion device accordingto claim 8 wherein said first electrode is directly formed on said frontsurface of the substrate.
 10. A photoelectric conversion deviceaccording to claim 8 wherein said substrate is flexible.
 11. Aphotoelectric conversion device according to claim 8 wherein saidphotoelectric conversion semiconductor layer comprises silicon.